U.S. patent application number 16/019362 was filed with the patent office on 2018-10-25 for base unit and disk drive apparatus.
The applicant listed for this patent is Western Digital Technologies, Inc.. Invention is credited to Takako Hayakawa, Jiro Kaneko, Yuta Onobu, Kimihiko Sudo.
Application Number | 20180308525 16/019362 |
Document ID | / |
Family ID | 59086543 |
Filed Date | 2018-10-25 |
United States Patent
Application |
20180308525 |
Kind Code |
A1 |
Kaneko; Jiro ; et
al. |
October 25, 2018 |
BASE UNIT AND DISK DRIVE APPARATUS
Abstract
A base member includes a recessed portion arranged to extend in
radial directions and recessed upward from a lower surface of the
base member, the radial directions being directions perpendicular
to a vertical direction or directions parallel to these directions;
and a hole portion arranged to pass through the recessed portion in
the vertical direction. The recessed portion includes a recessed
portion loop-shaped surface being a loop-shaped surface
perpendicular to the vertical direction. A connector is arranged on
a lower side of the recessed portion to cover the hole portion. An
adhesive is arranged between the connector and the recessed
portion. A minimum value of a gap distance between an outer end of
the connector and an inner end of the recessed portion in a radial
direction in which the outer end of the connector and the inner end
of the recessed portion are opposed to each other with the adhesive
therebetween is greater than a minimum value of a gap distance
between an upper surface of the connector and the recessed portion
loop-shaped surface in the vertical direction, in which the upper
surface of the connector and the recessed portion loop-shaped
surface are opposed to each other with the adhesive
therebetween.
Inventors: |
Kaneko; Jiro; (Yokohama-shi,
JP) ; Hayakawa; Takako; (Hiratsuka-shi, JP) ;
Sudo; Kimihiko; (Yokohama-shi, JP) ; Onobu; Yuta;
(Atsugi-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Western Digital Technologies, Inc. |
San Jose |
CA |
US |
|
|
Family ID: |
59086543 |
Appl. No.: |
16/019362 |
Filed: |
June 26, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15783128 |
Oct 13, 2017 |
10068622 |
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16019362 |
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15376797 |
Dec 13, 2016 |
9886984 |
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15783128 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11B 33/1466 20130101;
G11B 33/122 20130101; G11B 33/027 20130101; G11B 25/043
20130101 |
International
Class: |
G11B 33/14 20060101
G11B033/14; G11B 25/04 20060101 G11B025/04; G11B 33/02 20060101
G11B033/02; G11B 33/12 20060101 G11B033/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2015 |
JP |
2015-257080 |
Claims
1. A base unit for use in a disk drive apparatus in which a gas
having a density lower than that of air is sealed in a housing
space defined by a base member and a cover fixed to each other, the
base unit comprising: the base member, the base member being
arranged to support a motor rotatable about a central axis
extending in a vertical direction; and a connector electrically
connected to a wire arranged in the housing space; wherein the base
member includes: a recessed portion arranged to extend in radial
directions and recessed upward from a lower surface of the base
member, the radial directions being directions perpendicular to the
vertical direction or directions parallel to these directions; and
a hole portion arranged to pass through the recessed portion in the
vertical direction; the recessed portion includes a recessed
portion loop-shaped surface being a loop-shaped surface
perpendicular to the vertical direction; the connector is arranged
on a lower side of the recessed portion to cover the hole portion;
an adhesive is arranged between the connector and the recessed
portion; a minimum value of a gap distance between an outer end of
the connector and an inner end of the recessed portion in a radial
direction in which the outer end of the connector and the inner end
of the recessed portion are opposed to each other with the adhesive
therebetween is greater than a minimum value of a gap distance
between an upper surface of the connector and the recessed portion
loop-shaped surface in the vertical direction, in which the upper
surface of the connector and the recessed portion loop-shaped
surface are opposed to each other with the adhesive therebetween;
and the adhesive includes at least one of a glass bead and a metal
filler.
2. The base unit according to claim 1, wherein a surface of the
adhesive on a side closer to the hole portion is defined between
the upper surface of the connector and the recessed portion
loop-shaped surface.
3. The base unit according to claim 2, wherein the recessed portion
loop-shaped surface includes a first recessed portion loop-shaped
surface, and a second recessed portion loop-shaped surface arranged
on a side of the first recessed portion loop-shaped surface closer
to the hole portion; and the surface of the adhesive is defined at
the second recessed portion loop-shaped surface.
4. The base unit according to claim 1, wherein at least a portion
of a surface of the adhesive on a side opposite to a side closer to
the hole portion is defined between the upper surface of the
connector and the recessed portion loop-shaped surface.
5. The base unit according to claim 1, wherein the base member
includes a collar portion recessed upward and arranged to project
in a radial direction from an outer circumference of the recessed
portion; an extent to which the collar portion is recessed is
smaller than an extent to which the recessed portion loop-shaped
surface is recessed in the recessed portion; and the connector
includes a projecting portion arranged to project in the radial
direction from an outer circumference thereof to be arranged in the
collar portion.
6. A disk drive apparatus comprising: the base unit of claim 1; the
cover; the motor; and an access portion arranged to perform at
least one of reading and writing of information from or to a disk
supported by the motor; wherein the motor and the access portion
are accommodated in the housing space.
7. A base unit for use in a disk drive apparatus in which a gas
having a density lower than that of air is sealed in a housing
space defined by a base member and a cover fixed to each other, the
base unit comprising: the base member, the base member being
arranged to support a motor rotatable about a central axis
extending in a vertical direction; and a connector electrically
connected to a wire arranged in the housing space; wherein the base
member includes: a recessed portion arranged to extend in radial
directions and recessed upward from a lower surface of the base
member, the radial directions being directions perpendicular to the
vertical direction or directions parallel to these directions; and
a hole portion arranged to pass through the recessed portion in the
vertical direction; the recessed portion includes a recessed
portion loop-shaped surface being a loop-shaped surface
perpendicular to the vertical direction; the connector is arranged
on a lower side of the recessed portion to cover the hole portion;
an adhesive is arranged between the connector and the recessed
portion; and a minimum value of a gap distance between an outer end
of the connector and an inner end of the recessed portion in a
radial direction in which the outer end of the connector and the
inner end of the recessed portion are opposed to each other with
the adhesive therebetween is greater than a minimum value of a gap
distance between an upper surface of the connector and the recessed
portion loop-shaped surface in the vertical direction, in which the
upper surface of the connector and the recessed portion loop-shaped
surface are opposed to each other with the adhesive
therebetween.
8. The base unit according to claim 7, wherein a surface of the
adhesive on a side closer to the hole portion is defined between
the upper surface of the connector and the recessed portion
loop-shaped surface.
9. The base unit according to claim 8, wherein the recessed portion
loop-shaped surface includes a first recessed portion loop-shaped
surface, and a second recessed portion loop-shaped surface arranged
on a side of the first recessed portion loop-shaped surface closer
to the hole portion; and the surface of the adhesive is defined at
the second recessed portion loop-shaped surface.
10. The base unit according to claim 7, wherein at least a portion
of a surface of the adhesive on a side opposite to a side closer to
the hole portion is defined between the upper surface of the
connector and the recessed portion loop-shaped surface.
11. A disk drive apparatus comprising: the base unit of claim 7;
the cover; the motor; and an access portion arranged to perform at
least one of reading and writing of information from or to a disk
supported by the motor; wherein the motor and the access portion
are accommodated in the housing space.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to Japanese
Patent Application No. 2015-257080 filed on Dec. 28, 2015. The
entire contents of this application are hereby incorporated herein
by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to a base unit for use in a
disk drive apparatus.
Description of the Related Art
[0003] Disk drive apparatuses, such as, for example, hard disk
drive (HDD) apparatuses, are often arranged to rotate disks at high
speeds. In such an apparatus, each disk receives resistance caused
by a gas enclosed in the apparatus, and this may cause a vibration
of the disk and an error in reading or writing, an increase in a
power consumption of a motor, or other problems. In particular, in
recent years, the storage capacity of HDD apparatuses or the like
has been increasing, and the number of disks has been increasing,
and it has become important to take measures against the above
problems.
[0004] Accordingly, instead of air, a gas (which may be hereinafter
referred to as a low-density gas) having a density lower than that
of air is sealed in a known disk drive apparatus to reduce the
aforementioned resistance during rotation of the disk. As this
low-density gas, helium or the like is used, for example.
[0005] In such a disk drive apparatus, it is important to improve
the sealing in of the low-density gas. JP-A 2008-171482, for
example, discloses a disk drive apparatus including a base and a
cover, and having a low-density gas sealed in a housing space
defined by the base and the cover fixed to each other. In this disk
drive apparatus, a feedthrough, which is a connector of one type,
is joined to the base through a solder so as to close an opening
defined in the base to prevent the low-density gas from leaking out
of the base through the opening.
[0006] However, as noted in JP-A 2008-171482, a flange of the
feedthrough and the base have different coefficients of thermal
expansion, and therefore, an application of a stress to a solder
joint with low stress resistance might cause a crack in the solder
joint, resulting in a failure to sufficiently seal in the
low-density gas.
[0007] It is thus conceivable to use an adhesive which is more
resistant to heat shock than the solder and is also inexpensive as
a material for joining the base and the connector to each
other.
SUMMARY OF THE INVENTION
[0008] A base unit according to a preferred embodiment of the
present invention is a base unit for use in a disk drive apparatus
in which a gas having a density lower than that of air is sealed in
a housing space defined by a base member and a cover fixed to each
other. The base unit includes the base member, the base member
being arranged to support a motor rotatable about a central axis
extending in a vertical direction; and a connector electrically
connected to a wire arranged in the housing space. The base member
includes a recessed portion arranged to extend in radial directions
and recessed upward from a lower surface of the base member, the
radial directions being directions perpendicular to the vertical
direction or directions parallel to these directions; and a hole
portion arranged to pass through the recessed portion in the
vertical direction. The recessed portion includes a recessed
portion loop-shaped surface being a loop-shaped surface
perpendicular to the vertical direction. The connector is arranged
on a lower side of the recessed portion to cover the hole portion.
An adhesive is arranged between the connector and the recessed
portion. A minimum value of a gap distance between an outer end of
the connector and an inner end of the recessed portion in a radial
direction in which the outer end of the connector and the inner end
of the recessed portion are opposed to each other with the adhesive
therebetween is greater than a minimum value of a gap distance
between an upper surface of the connector and the recessed portion
loop-shaped surface in the vertical direction, in which the upper
surface of the connector and the recessed portion loop-shaped
surface are opposed to each other with the adhesive
therebetween.
[0009] The base unit according to a preferred embodiment of the
present invention is able to improve the sealing in of the
low-density gas in a structure in which the connector is fixed to
the base member through the adhesive.
[0010] The above and other elements, features, steps,
characteristics and advantages of the present invention will become
more apparent from the following detailed description of the
preferred embodiments with reference to the attached drawings.
[0011] The above and other elements, features, steps,
characteristics and advantages of the present invention will become
more apparent from the following detailed description of the
preferred embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a vertical sectional view of a disk drive
apparatus according to a preferred embodiment of the present
invention.
[0013] FIG. 2 is a top plan view of a base unit according to a
preferred embodiment of the present invention.
[0014] FIG. 3 is a bottom plan view of the base unit.
[0015] FIG. 4 is an exploded perspective view of an airtight
structure realized by a connector, illustrating a base member as
viewed from below, according to a preferred embodiment of the
present invention.
[0016] FIG. 5 is a side sectional view of the connector and a
bottom portion fixed to each other taken along a line that does not
pass through any collar portion according to a preferred embodiment
of the present invention.
[0017] FIG. 6 is a side sectional view of the connector and the
bottom portion fixed to each other taken along a line that passes
through any collar portion according to a preferred embodiment of
the present invention.
[0018] FIG. 7 is a graph illustrating example relationships between
a gap distance between the connector and the base member and the
amount of a leakage of sealed-in helium.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] Hereinafter, exemplary preferred embodiments of the present
invention will be described with reference to the accompanying
drawings. It is assumed herein that a direction in which a central
axis about which a spindle motor is rotatable extends is referred
to by the term "vertical direction", "vertical", or "vertically",
and that directions perpendicular to the vertical direction and
directions parallel to these directions are each referred to by the
term "radial direction", "radial", or "radially". It is also
assumed herein that a direction along a circular arc centered on
the central axis is referred to by the term "circumferential
direction", "circumferential", or "circumferentially". It is also
assumed herein that the side on which a cover is arranged with
respect to a base member is an upper side in the vertical
direction. The shape of each member or portion and relative
positions of different members or portions will be described based
on the above assumptions. Note, however, that the above definitions
of the vertical direction and the upper and lower sides are simply
made for the sake of convenience in description, and should not be
construed to restrict the orientation of a base unit or a disk
drive apparatus according to any preferred embodiment of the
present invention when in use.
[0020] FIG. 1 is a vertical sectional view of a disk drive
apparatus 1 according to a preferred embodiment of the present
invention. The upper side in FIG. 1 corresponds to the upper side
in the vertical direction. The disk drive apparatus 1 is an
apparatus arranged to perform reading and writing of information
from or to magnetic disks 4 while rotating the magnetic disks 4.
The disk drive apparatus 1 includes a base unit 2, a spindle motor
3, the magnetic disks 4, a cover 5, and an access portion 6.
[0021] The base unit 2 includes a base member 21 arranged to
support the spindle motor 3, and a connector 22. The spindle motor
3 is capable of rotating about a central axis J1. The spindle motor
3 is arranged to rotate the magnetic disks 4, which are three in
number, about the central axis J1 while supporting the magnetic
disks 4. The spindle motor 3 and the access portion 6 are
accommodated in a housing space of a case defined by the base
member 21 and the cover 5. The access portion 6 is arranged to move
heads 61 along recording surfaces of the magnetic disks 4 to
perform the reading and the writing of information from or to the
magnetic disks 4.
[0022] The cover 5 is joined and fixed to the base member 21 on the
upper side of the base member 21. A junction of the base member 21
and the cover 5 is sealed by a sealant, such as an elastomer, or an
adhesive, or through welding, for example. In addition, a gas
having a density lower than that of air is sealed in the housing
space of the case defined by the base member 21 and the cover 5. As
the low-density gas, a helium gas, a nitrogen gas, a mixture of
helium and nitrogen gases, or the like is preferably used. This
contributes to reducing resistance applied to each magnetic disk 4,
and thus to reducing vibrations of the magnetic disks 4 which occur
during rotation, and minimizing an increase in a power consumption
of the motor 3.
[0023] Note that the disk drive apparatus 1 may alternatively be
arranged to include one, two, or more than three magnetic disks.
Also note that the access portion 6 may alternatively be arranged
to perform only one of the reading and the writing of information
from or to the magnetic disks 4.
[0024] The spindle motor 3 includes a stator 31, a rotating portion
32, and a stationary portion 33. The stator 31 includes coils 311.
The stator 31 is fixed to an outer circumference of a bearing
fixing portion 213 of the base member 21. The bearing fixing
portion 213 is arranged to project upward from a bottom portion 211
of the base member 21 to assume a substantially cylindrical
shape.
[0025] The rotating portion 32 includes a rotor hub 321 and a rotor
magnet 322. A shaft hole portion 321A extending in the vertical
direction is defined in a center of the rotor hub 321. The rotor
hub 321 is arranged to support the magnetic disks 4. The stationary
portion 33 includes a shaft 331, a first cone portion 332, and a
second cone portion 333. The shaft 331 is inserted through the
shaft hole portion 321A of the rotor hub 321. The shaft 331 is
inserted and fixed in an opening portion 213A defined inside of the
bearing fixing portion 213, and is thus held while being oriented
in the vertical direction along the central axis J1. Each of the
first and second cone portions 332 and 333 is fixed to the shaft
331. While the spindle motor 3 is running, a fluid dynamic pressure
is generated in a lubricating oil in a gap between the rotor hub
321 and each of the first and second cone portions 332 and 333. The
rotor hub 321 is thus supported to be rotatable with respect to the
shaft 331.
[0026] The access portion 6 includes the heads 61, arms 62, and a
head actuator mechanism 63. Two of the heads 61 and two of the arms
62 are provided for each one of the magnetic disks 4. Each of the
two arms 62 supports one of the heads 61. Each head is arranged to
perform the reading and the writing of information while being
arranged in close proximity to the corresponding magnetic disk 4.
The head actuator mechanism 63 is arranged to actuate each of the
arms 62 to move an associated one of the heads 61 relative to a
corresponding one of the magnetic disks 4. The head 61 is thus
arranged to make access to a desired location on the rotating
magnetic disk 4 while being arranged in close proximity to the
magnetic disk 4, to carry out the reading and the writing of
information. Note that the head 61 may be arranged to perform at
least one of the reading and the writing of information from or to
the magnetic disk 4.
[0027] FIG. 2 is a top plan view of the base unit 2. The base
member 21 of the base unit 2 is a metal member made of, for
example, aluminum. The bottom portion 211 and a side wall portion
212 of the base member 21 are molded by a die casting process as a
single continuous monolithic member.
[0028] The side wall portion 212 includes a partially cylindrical
side surface 212A. The partially cylindrical side surface 212A is a
portion of an inside surface of the side wall portion 212. The
partially cylindrical side surface 212A is a portion of a
cylindrical surface centered on the central axis J1. The partially
cylindrical side surface 212A is arranged opposite to an outer
circumference of each magnetic disk 4, which is arranged inside of
the partially cylindrical side surface 212A. The partially
cylindrical side surface 212A is defined inside of the side wall
portion 212 by a cutting process, and is coated with a coating
agent through electrodeposition coating. Note that the above
coating using the coating agent is not limited to the
electrodeposition coating, but may alternatively be accomplished
through spray coating or the like, for example. This is also true
of coating of another portion which will be described below as
being accomplished through electrodeposition coating.
[0029] The base member 21 includes the bottom portion 211. The
bottom portion 211 includes a disk opposing bottom surface 211A.
The disk opposing bottom surface 211A is a portion of an upper
surface of the bottom portion 211. The disk opposing bottom surface
211A is a portion of a substantially annular surface centered on
the central axis J1. The disk opposing bottom surface 211A is
arranged opposite to a lower surface of the magnetic disk 4
arranged above. The disk opposing bottom surface 211A is defined by
a cutting process after the die casting process, and is coated with
a coating agent through electrodeposition coating.
[0030] The shaft 331 of the spindle motor 3 is fixed to the bearing
fixing portion 213 as suggested above. The bearing fixing portion
213 is defined inside of the disk opposing bottom surface 211A by a
cutting process.
[0031] After the die casting process, a head actuator mechanism
fixing portion 214 is defined by a cutting process at a position
away from the partially cylindrical side surface 212A and the disk
opposing bottom surface 211A. The head actuator mechanism fixing
portion 214 is arranged to project upward from the bottom portion
211. The head actuator mechanism fixing portion 214 is arranged to
rotatably fix a portion of the head actuator mechanism 63.
[0032] FIG. 3 is a bottom plan view of the base unit 2. An FPC
mounting portion 211B is defined in a lower surface of the bottom
portion 211. The FPC mounting portion 211B is a portion slightly
recessed upward and on which a first FPC (a flexible printed
circuit board), which is not shown, is mounted. The FPC mounting
portion 211B is defined in the vicinity of the shaft 331 when
viewed from below.
[0033] Here, a control circuit board (not shown) is fixed to the
lower surface of the bottom portion 211 on the lower side in FIG.
3. Various circuits are formed on the control circuit board. The
control circuit board is electrically connected to one end portion
of the first FPC mounted on the FPC mounting portion 211B. Lead
wires extending from the coils 311 (see FIG. 1) included in the
stator 31 are electrically connected to another end portion of the
first FPC. This allows electric currents to be supplied from a
drive circuit formed on the control circuit board to the coils 311
through the first FPC to drive the spindle motor 3 to rotate.
[0034] In addition, a hole portion 215 (see FIG. 2) passing through
the bottom portion 211 in the vertical direction is defined in the
bottom portion 211 at a position away from the head actuator
mechanism fixing portion 214. The connector 22, which is defined by
a feedthrough, is fixed to the lower surface of the bottom portion
211 through an adhesive. In the situation in which the connector 22
is thus fixed, terminals T1 arranged in an upper surface of the
connector 22 are exposed upwardly through the hole portion 215.
Terminals T2 (see FIG. 3) each of which corresponds to a separate
one of the terminals T1 are arranged in a lower surface of the
connector 22. The control circuit board is arranged to cover the
lower surface of the connector 22, and is electrically connected to
each terminal T2.
[0035] Here, as illustrated in FIG. 1, the disk drive apparatus 1
includes an FPC connector 7 and a second FPC 8. The FPC connector 7
is arranged on the upper side of the bottom portion 21. A portion
of the FPC connector 7 is passed through the hole portion 215 to be
electrically connected to each terminal T1. The FPC connector 7 is
electrically connected to one end portion of the second FPC 8.
Another end portion of the second FPC 8 is electrically connected
to the head actuator mechanism 63.
[0036] This enables a signal read by any of the heads 61 to be
transmitted from the head actuator mechanism 63 to the control
circuit board through the second FPC 8, the FPC connector 7, and
the connector 22, and also enables a signal to be written by any of
the heads 61 to be transmitted from the control circuit board to
the head actuator mechanism 63 through the connector 22, the FPC
connector 7, and the second FPC 8. It is also made possible to
transmit a drive signal from the drive circuit formed on the
control circuit board to a voice coil motor (not shown) included in
the head actuator mechanism 63 through the connector 22, the FPC
connector 7, and the second FPC 8.
[0037] Next, an airtight structure realized by the connector 22,
which is defined by the feedthrough, to seal in the low-density gas
will now be described in detail below. FIG. 4 is an exploded
perspective view of the airtight structure realized by the
connector 22, illustrating the base member 21 as viewed from below.
That is, the lower side in FIG. 4 corresponds to the upper
side.
[0038] The bottom portion 211 of the base member 21 includes a
recessed portion 216 which extends in radial directions and is
recessed upward from the lower surface of the bottom portion 211.
The recessed portion 216 includes a recessed portion loop-shaped
surface S, which is a loop-shaped surface perpendicular to the
vertical direction. The recessed portion 216 is recessed in two
steps from the lower surface of the bottom portion 211.
Accordingly, the recessed portion loop-shaped surface S includes a
first recessed portion loop-shaped surface S1, which is defined by
a first-step recess, and a second recessed portion loop-shaped
surface S2, which is defined by a second-step recess.
[0039] The hole portion 215, which passes through an area enclosed
by the second recessed portion loop-shaped surface S2 in the
vertical direction, is defined in the bottom portion 211. In other
words, the base member 21 includes the hole portion 215 passing
through the recessed portion 216 in the vertical direction. The
second recessed portion loop-shaped surface S2 is arranged on the
side of the first recessed portion loop-shaped surface S1 closer to
the hole portion 215.
[0040] The bottom portion 211 includes collar portions 217A, 217B,
and 217C each of which is recessed upward and projects in a radial
direction from an outer circumference of the recessed portion 216.
The collar portions 217A and 217B are arranged to project from
opposed sides of an outer peripheral edge of the recessed portion
216. The collar portion 217C is arranged to project from a side
that joins the above opposed sides. The extent to which each of the
collar portions 217A to 217C is recessed is smaller than the extent
to which the first recessed portion loop-shaped surface S1 is
recessed in the recessed portion 216.
[0041] The connector 22 includes a plate-shaped base portion 221
and a body portion 222 arranged to project downward from the base
portion 221. The terminals T2 are arranged in a lower surface of
the body portion 222. The terminals T1 (see FIG. 2), which are not
shown in FIG. 4, are arranged in an upper surface of the base
portion 221. The base portion 221 includes projecting portions
221A, 221B, and 221C each of which is arranged to project in a
radial direction from an outer circumference thereof. The
projecting portions 221A, 221B, and 221C correspond to the collar
portions 217A, 217B, and 217C, respectively. Although, in the
present preferred embodiment, the collar portions 217A to 217C are
arranged at three positions, and the projecting portions 221A to
221C are arranged at three corresponding positions, this is not
essential to the present invention. For example, only two collar
portions parallel to each other and only two projecting portions
parallel to each other may be arranged, and also, collar portions
and projecting portions may both be arranged at more than three
positions.
[0042] A method by which the connector 22 is fixed to the base
member 21 will now be described below. Note that, when the
connector 22 is fixed thereto, a lower surface of the base member
21 is arranged to face in a direction opposite to the direction of
gravity (that is, the direction of gravity points downward in FIG.
4). An adhesive is applied onto the first recessed portion
loop-shaped surface S1 such that the adhesive will extend all the
way around the hole portion 215. As this adhesive, an anaerobic
adhesive, for example, is used. With the adhesive applied on the
first recessed portion loop-shaped surface S1, the projecting
portions 221A to 221C of the connector 22 are pressed against upper
surfaces of the collar portions 217A to 217C, respectively. The
connector 22 is thus arranged on the lower side of the recessed
portion 216 to cover the hole portion 215. The adhesive intervenes
between the connector 22 and the recessed portion 216. The
projecting portions 221A to 221C are arranged in the collar
portions 217A to 217C, respectively. As a result of the adhesive
being cured, the connector 22 is fixed to the base member 21. The
adhesive preferably includes at least one of a glass bead and a
metal filler to achieve an improvement in the sealing in of the
low-density gas.
[0043] FIG. 5 is a side sectional view of the connector 22 and the
bottom portion 211 fixed to each other taken along a line that does
not pass through any of the collar portions 217A to 217C. As
illustrated in FIG. 5, an adhesive 9 is arranged between the base
portion 221 of the connector 22 and the recessed portion 216. The
adhesive 9 intervenes between an outer end of the base portion 221
and an inner end of the recessed portion 216 and between the upper
surface of the base portion 221 and the first recessed portion
loop-shaped surface S1.
[0044] A minimum value of a gap distance X between the outer end of
the base portion 221 and the inner end of the recessed portion 216
in a radial direction in which the outer end of the base portion
221 and the inner end of the recessed portion 216 are opposed to
each other with the adhesive 9 therebetween is greater than a
minimum value of a gap distance Y between the upper surface of the
base portion 221 and the first recessed portion loop-shaped surface
S1 in the vertical direction, in which the upper surface of the
base portion 221 and the first recessed portion loop-shaped surface
S1 are opposed to each other with the adhesive 9 therebetween.
[0045] Here, FIG. 7 is a graph illustrating example relationships
between the gap distance between the connector and the base member
and the amount of a leakage of sealed-in helium (which is an
example of the low-density gas). The horizontal axis in FIG. 7
represents minimum values (which are 0.1 mm, 0.2 mm, and 0.3 mm) of
the gap distance between the connector and the base member. The
vertical axis in FIG. 7 represents the amount of the leakage of
helium sealed in the housing space defined by the base member and
the cover.
[0046] Hatched areas in FIG. 7 represent the amount of a leakage
due to a cause other than the gap (for example, a leakage through
the connector itself, a leakage due to a hole through which a coil
wire of the motor is drawn out, or the like). In the case where the
connector is fixed to the base member through a solder, the solder
is arranged in the gap. As illustrated in FIG. 7, the amount SL of
a leakage of helium in this case does not depend on the gap
distance, but corresponds to an amount represented by each hatched
area. That is, in the case where the connector is fixed to the base
member through the solder, the amount of the leakage of helium
through the gap is substantially zero regardless of the size of the
gap.
[0047] In contrast, in the case where the connector is fixed
through an adhesive, the adhesive is arranged in the gap. The
amount of a leakage of helium through the gap in this case is
represented by a black area in FIG. 7. That is, the sum total of
the amount of the leakage represented by the hatched area and the
amount of the leakage represented by the black area corresponds to
the total amount of the leakage of helium. As illustrated in FIG.
7, the amount of the leakage through the gap as represented by the
black area decreases as the gap distance decreases. Thus, when the
gap distance has a large value, 0.3 mm, the total amount of the
leakage of helium exceeds a tolerance threshold value Th. Then,
when the gap distance is reduced to 0.2 mm and 0.1 mm, the total
amount of the leakage is below the tolerance threshold value Th.
Therefore, when the minimum value of the gap distance between the
connector and the base member is arranged to be 0.2 mm or less, the
total amount of the leakage of helium does not exceed the tolerance
threshold value Th. Adjustment of the gap distance is important
when not a solder but an adhesive is used to fix the connector.
[0048] As described above, in the present preferred embodiment, the
minimum value of the gap distance X as illustrated in FIG. 5 is
arranged to be greater than the minimum value of the gap distance
Y, and therefore, a narrow gap having the gap distance Y can be
defined, and the adhesive 9 can be forced into this gap by
capillary action. The minimum value of the gap distance X is
arranged to be, for example, 0.5 mm, and the minimum value of the
gap distance Y is arranged to be, for example, 0.2 mm or less. This
contributes to effectively preventing the low-density gas sealed in
the housing space defined by the base member 21 and the cover 5
from leaking out through the hole portion 215 and the gap having
the gap distance Y.
[0049] Further, because the adhesive 9 is actively forced toward
the upper side of the base member 21 by capillary action, the
likelihood that the adhesive 9 will leak out to the lower side of
the base member 21 is reduced. This in turn reduces the likelihood
that a portion of the adhesive 9 will leak out to be attached to
the control circuit board, causing a failure of the spindle motor 3
to rotate or another malfunction.
[0050] Furthermore, the adhesive 9, which is pressed by the
connector 22 at the time of the adhesion of the connector 22,
travels longer distances in narrower gaps. Therefore, the adhesive
9 can be actively forced into the narrow gap having the gap
distance Y, which is defined in the present preferred
embodiment.
[0051] Although, in FIG. 5, a surface R1 of the adhesive 9 on the
side closer to the hole portion 215 is defined between the upper
surface of the base portion 221 and the first recessed portion
loop-shaped surface S1, the surface R1 may alternatively be defined
between the upper surface of the base portion 221 and the second
recessed portion loop-shaped surface S2. This allows the adhesive 9
to be more actively forced toward the upper side of the base member
21.
[0052] A portion of a surface R2 of the adhesive 9 on the side
opposite to the side closer to the hole portion 215 is defined
between the upper surface of the base portion 221 and the first
recessed portion loop-shaped surface S1. At the time of the
adhesion of the connector 22, the adhesive 9 does not easily travel
in the wider gap having the gap distance X, and the adhesive 9 can
be actively forced into the narrower gap having the gap distance
Y.
[0053] The recessed portion loop-shaped surface S is arranged to
have a degree of surface roughness greater than the degree of
surface roughness of the upper surface of the base portion 221.
This contributes to preventing the adhesive 9 from leaking out to
the upper side of the base member 21 through the hole portion 215
after traveling along the recessed portion loop-shaped surface
S.
[0054] Each of the outer end of the base portion 221 and the inner
end of the recessed portion 216 is arranged to have a degree of
surface roughness greater than the degree of surface roughness of
the upper surface of the base portion 221. This contributes to
preventing the adhesive 9 from leaking out to the lower side of the
base member 21 to be attached to the control circuit board or the
like.
[0055] FIG. 6 is a side sectional view of the connector 22 and the
bottom portion 211 fixed to each other taken along a line that
passes through any of the collar portions 217A to 217C. In the
following description, the collar portion 217A is chosen as a
representative for the sake of convenience. As illustrated in FIG.
6, at the time of the adhesion of the connector 22, the adhesive 9
is pressed by the base portion 221, and an upper surface of the
projecting portion 221A is pressed against an upper surface of the
collar portion 217A. This easily achieves the positioning of the
connector 22 in the vertical direction.
[0056] As a result, the adhesive 9 intervenes between the upper
surface of the base portion 221 and the first recessed portion
loop-shaped surface S1, and between an outer end of the projecting
portion 221A and an inner end of the collar portion 217A. In
addition, the adhesive 9 also intervenes in a very narrow gap
between the upper surface of the projecting portion 221A and the
upper surface of the collar portion 217A.
[0057] While preferred embodiments of the present invention have
been described above, the preferred embodiments may be modified in
various manners without departing from the scope and spirit of the
present invention.
[0058] For example, the connector used to seal in the low-density
gas is not limited to the feedthrough as described above, but may
alternatively be a connector defined by a low temperature co-fired
ceramic (LTCC).
[0059] Also note that an additional first-step recess having a
loop-shaped surface arranged at a level lower than that of the
first recessed portion loop-shaped surface S1 according to the
above-described preferred embodiment may be defined all the way
around the hole portion 215. In this case, the recessed portion
includes three recessed portion loop-shaped surfaces. In this case,
the base portion of the connector is not provided with the
projecting portions, and an outer edge portion of the base portion
is pressed against the loop-shaped surface of the above recess all
the way around the hole portion 215 to accomplish the adhesion of
the connector.
[0060] Preferred embodiments of the present invention are
applicable to disk drive apparatuses, such as, for example,
HDDs.
[0061] While preferred embodiments of the present invention have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present invention. The
scope of the present invention, therefore, is to be determined
solely by the following claims.
[0062] While preferred embodiments of the present invention have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present invention. The
scope of the present invention, therefore, is to be determined
solely by the following claims.
* * * * *